I had the same problem with a buddy of mine who is 6'7 with ape arms. His biggest problem was that the mounts I had on all my ar's were to close for him. We ended up putting a burris pepr mount with a RRA operator stock. Granted he has to shoulder the weapon different than his shotgun or his other rifles. He has been totally happy with it. I was able to let him try 4 different stocks before he picked the operator. With a heavy coat on it is more than long enough. One thing that we did was make sure that when he mounts the weapon to have the bottom of the stock high up in the shoulder area not low like most shotguns and rifles. Just food for thought. If you want to try a couple different stocks I have lowers with a PRS,operator and magpul MOE and an a2. I'm not too far away from you.